The present invention relates to a wireless tire condition monitoring apparatus that allows a driver in a vehicle passenger compartment to check vehicle tire condition such as an air pressure, and to a transmitter and a receiver that are used for the apparatus.
Wireless tire condition monitoring apparatuses that allow a driver in a vehicle passenger compartment to check the condition of vehicle tires have been proposed. A tire condition monitoring apparatus includes transmitters and a receiver. Each of the transmitters is attached to the wheel rim of the tire so as to be located in the tire, and the receiver is located in the body frame of the vehicle. The transmitter detects the condition of the corresponding tire, such as the internal pressure and the interior temperature of the tire, and wirelessly transmits a signal including the detection data of the tire condition via an antenna. The receiver receives the signal having been wirelessly transmitted from the transmitter and displays information about the tire condition on a display when necessary. The display is located, for example, in the passenger compartment.
Other tire condition monitoring apparatuses are conventionally proposed that transmit and receive a signal including the detection data of the tire condition together with identification information (ID code), which is set for each tire, and identify the detection data and the position of the tire (for example, Patent Document 1: Japanese Patent No. 3212311). In such conventional apparatuses, a specific identification code is given to each transmitter. Each transmitter transmits signals that include data of tire condition and a given ID code.
On the other hand, the ID codes of all the transmitters associated with the vehicle on which the receiver is mounted are registered in the receiver. When the ID code included in the received signal matches with one of the registered ID codes, the receiver locates the position of the tire according to the ID code and continues processing the received signal. However, if the ID code included in the received signal differs from all of the registered ID codes, the receiver does not process the received signal. Therefore, the receiver is prevented from erroneously processing signals from a transmitter of another vehicle that is not associated with the vehicle on which the receiver is mounted.
However, in the conventional apparatus of Patent Document 1, prior to the monitoring of tire condition, it is necessary to switch an operation mode of the receiver from a tire condition monitoring mode to an ID code registration mode, and it is necessary to set and register the ID code of the transmitter for each tire. Thus, the registration of ID codes becomes troublesome and the monitoring of tire condition cannot be started quickly.